There are many diseases and disorders associated with increased infiltration of fat in muscle, e.g., muscle atrophy. Muscle atrophy is associated with cancer, AIDS, renal failure, liver disease, spinal cord injury, and congestive heart failure. Furthermore, disuse of muscles through immobilization or aging also results in muscle atrophy with increased fat infusion in muscle.
The gold standard for treating muscle atrophy conditions is recovery of function. However, direct assessment of muscle functional muscle mass is challenging (Evans et al., 2019, Journal of Cachexia, Sarcopenia and Muscle, 10:14-21). Furthermore, the ability to reduce infiltration of fat in muscle is an important therapeutic target, with few if any pharmacological agents available.
Thus, there is a need to identify pharmacological methods of reducing fat infiltration in muscle, and to use such agents to reduce fat infiltration in muscle, particularly under conditions of muscle atrophy. Furthermore, there is a need to identify markers of functional muscle mass to develop additional metabolic rebalancing compositions for enhancing muscle mass and function (relative to not receiving any therapy), such as for treating muscle-related disease and disorders where fat infiltration in muscle occurs.